By following this tutorial, you can learn how to easily make a train whistle sound using only your hands. By simply folding your hands and adjusting for the air flow as you blow on your thumb knuckles, you can replicate the sound of a train whistle. This is a very easy trick to learn so with just a little practice, you can use the train whistle to play with your kids, call them to dinner, etc. A great trick for somebody who has difficulty with conventional whistling.